Karteikarten
L3 Stats- Statistical Report flashcards
Karten in diesem Stapel (16)
- 1Censusincludes all members of the target population
- 2A Sampleincludes some members of the target population
- 3Target populationgroups of people that they want to find information on.
- 4What are the benefits of taking samplesthey Reduce cost and reduce effort needed.
Researchers get info on populations without having to survey them in their entirety. - 5Types of sampling methods includeStratified Sampling
Cluster Sampling
Random Sampling
Systematic Sampling - 6What is Random SamplingRandom sampling is were every individual in a population is listed and then members are selected with a random process to create a sample
Eg: pull names out of a hat - 7What is Cluster samplingthe population already contains subset groups that are representative of the population.
Eg: 8 schools are selected from Auckland to represent the regions schools - 8What is Stratified samplingthe population is split into subgroups or 'strata'. Samples are taken from each subgroup that is proportional to the size of the population.
Eg: 5 kids are picked from each small high schools in Aukland, 10 kids are picked from each large school in Auckland to be representative of all Auckland schools. - 9What is Systematic samplingEvery individual of a population is listed and a systematic rule is used to select a sample of them.
Eg: every third person in the phone book. - 10How do Sampling Errors occur- occur due to random chance
-As sampling size increases sampling errors decrease
-errors are more likely to occur in samples of small groups
- Sampling errors can be minimised but never fully be avoided due to variability between samples - 11How do Non- Sampling errors occur-purely occur due to how the information from the sample was collected.
- generally means the sample is non representative of the population and causes bias.
eg: low response rates to a survey, answers that aren't useful, people are hard to reach are not represented in the survey, false answers deliberately given. - 12Confidence Intervalsa range of values in which the true population proportions are likely to lie within.
Based on the sample proportion - 1395% confidence intervalsa 95 % confidence interval for a population means that if we were to repeat the sampling 100 times , 95 times the population proportion would be within our proposed confidence intervals.
- 14Calculating confidence intervalsconfidence interval using population proportions = p +/- z √ p x (1-p) / n
p= population proportion
n= sample size
z= changes depending on what CI - 15Margins of Error (MoE)* MoE= z√ p x (1-p) / n
OR
use the easier rule of thumb
(provided the proportion is between 0.3 and 0.7)
* MoE= 1 / √ n - 16values for Z=for 95% z= 1.96
for 99% z= 2.576
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- NCEA Level 2 Mathematics Karteikarten am L3 Stats- Statistical Report flashcards, erstellt von Sophie Painter am 09/09/2018.
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- Sophie Painter
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